Asked To Pay Back Bonus And Exgratia By Private Sector Bank - Legal?

Hi...
I worked in a private sector bank for last 8 years as clerk. Last month I resigned from job due to some personal issues.I have also served my notice period of one month.
I had OD Account and I have adjusted it.
Now to get a proper reliving order and my original certificates from banks HR department, they have asked me to pay back the exgratia and bonus paid to me for last financial year.
Kindly advice on whether it is a right claim by bank and what I should do further.

It is unfair to demand to pay back an amount especially an amount to which an employee is legally eligible to get in order to get relieved from duties. You should raise it as an industrial dispute. The bank has done an illegal act by collecting the educational certificates also. Holding the same is again an offence and you should fight for that.
Madhu.T.K